Cytokines and growth factors

This article surveys the growth factors that underpin organoid culture, why they matter, and how their delivery shapes organoid quality, reproducibility and cost. It explains the roles of the core signalling families, why stem-cell niches depend on tightly regulated factor gradients, and how the practical challenges of growth factor instability and expense are driving interest in sustained-release approaches.

Activin A is the single most important growth factor in iPSC differentiation toward endoderm-derived lineages, and one of the most widely used in cardiac mesoderm protocols as well.

In cell biology, immunology, and drug development, cytokines and growth factors are rarely discussed purely in terms of mass. Instead, their potency is often expressed in International Units (IU) a convention that can confuse even experienced researchers. Why are some cytokines defined in IU, others sold only by weight, and why do IU values seem to vary between suppliers?

Affinity-based biosensors use antibodies or aptamers to detect cytokines but suffer from slow dissociation kinetics (half-lives up to ~20 hours). Addressing this kinetic bottleneck enables real-time monitoring of concentration.

Macrophages are key immune cells that constantly identify and remove emerging cancers. Unfortunately, some cancer cells slip under the macrophage radar. When these immuno-escaped cancer cells develop the ability to control macrophages, cancers can become enabled to metastasise. However, this reliance on macrophages could provide therapeutic opportunities.

Last week, two groups reported encouraging clinical trial results of iPSC-based autologous cellular therapy for Parkinsons disease (PD). However, the implanted cells' poor survival may have undermined these results.

Immunotherapy, boosting the activity of the immune system, is widely used in cancer treatment. Success has been achieved with a variety of modalities, including adoptive cellular immunotherapy, antibodies, tumour vaccines, and small-molecule inhibitors. Tumour-associated macrophages (TAMs) play a key role in treatment outcome for many of these modalities even if the treatment does not target them directly.

Cells communicate by their secretions, impacting the behaviour of other cells. Cell secretion therapies use living cells to produce and secrete therapeutic substances that can aid in treating diseases. These include extracellular vesicles (EVs), cytokines, chemokines and hormones. Such therapies are at the forefront of regenerative medicine and immunotherapy.

In biomanufacturing, growth factors and cytokines are crucial for the cultivation and maintenance of cell cultures, particularly in the production of therapeutic proteins, vaccines, and other biologics. Just a few growth factors are widely used.

Chemokines are promising modalities in the treatment of disease. These small signaling proteins, primarily known for their role in directing the movement of immune cells, are now being explored for their therapeutic potential in a range of conditions, from cancer to chronic inflammatory diseases.